Electric circuit breaker



ELECTRIC CIRCUIT BREAKER Filed Jan. 25, 1936 4 Sheecs--Sheel l Jah. 17, 1939. A. HALL'ER ET AL 2,144,372

ELECTRIC' CIRCUIT BREAKER Fld Jan. 25, 19H36 4 Sheets-Sheet 2 Jan. 17, L'1939. A, HApLER Er AL 2,144,372

ELECTRIC CIRCUIT BREAKER Filed Jan. 23, 1936 4 Sheets-Sheet 3 czasfo i ra rzosf Jan. 17, 1939. A. HALLER r-:r A1. 2,144,372

ELECTRIC CIRCUIT BREAKER Filed Jan. 23, 195e 4 sheets-sheet 4 I .I I 7//////////////// Patented Jan. 17, 1939` 2,144,372

UNITED sTATEs PATENT OFFICE ELECTRIC CIRCUIT BREAKER Arnold Haller and Hans Thommen, Baden, Switzerland, assignors to Aktiengesellschaft Brown Boveri & Cie, Baden, Switzerland, a joint-stock company of Switzerland i Application January 23, 1936, Serial No. 60,362 In Germany January 30, 1935 12 Claims. (Cl. 200-148) This invention relates in general to improvefluid blast type which overcomes the above stated ments in electric circuit breakers and more pardisadvantages and which is of simple constructicularly to circuit breakers of the fluid blast tion and reliable in operation. type in which the functions of interrupting the Another object of the present invention is to flow of current in a circuit, and of thereafter provide a circuit breaker of the fluid blast type 5 maintaining the circuit open, are performed by in which a disconnecting contact is rigidly fasseparate contacte tened to a movable arcing contact of the breaker.

In the operation of circuit breakers of the fluid Another object of the present invention is to blast type, the current interruption takes place provide a circuit breaker of the fluid blast type under the most advantageous conditions when in which arcing and disconnecting contacts are l0 the arcing contacts are rapidly separated to a sequentially operated by separate mechanisms distance permitting the ow of a lateral blast of operable at predetermined speeds. fluid of maximum velocity between the contacts, Another object oi the present invention is to the circuit being opened permanently by means provide a circuit breaker of the fluid blast type l5 of disconnecting contacts which are opened after having a disconnecting contact' actuated by a l5 the arc has been extinguished and while the fluid pressure operated motor provided with fluid blast is stili being maintained. To obtain a means for insuring complete operation of the proper relationship between the operating speeds contact. of the arcing and disconnecting contacts, sepa- Another object of the present invention is to 2o rate actuating means are preferably provided provide a circuit breaker of the iluid blast type 20 therefor, and means, which may include interprovided with a mechanism permitting the cirlocks, are provided for insuring the sequential cuit breaker to open immediately after it is operation of the arcing and disconnecting concaused to close on a faulty circuit. tacts. Such an arrangement, which comprises Objects and advantages other than those above 3,1 in effect two complete separate switching deset forth will be apparent from the following devices, may lead to the disadvantage of a design scription when read in connection with the acrequiring a considerable amount of space and companying drawings, in which: involving an excessive cost. Fig. 1 is a side elevational view of a circuit Such disadvantages are obviated by actuating breaker built in accordance with the present in- ;m the two switching devices by fluid pressure opervention and provided with an electro-responsive 3o ated means, and by solidly connecting the movrelay for mechanically causing operation of the able arcing contact of the circuit breaker with circuit breaker upon flow of excessive current one of the disconnecting contacts thereof. The therethrough; arc drawn between the arcing contacts is blown Fig. 2 is an enlarged axial cross section through into a deionizing chamber for preventing an exthe arcing chamber of the embodiment illus- 35 cessive rextension thereof. Means are preferably trated in Fig. 1 taken in a plane parallel to the provided for insuring immediate reclosure of the plane of projection utilized in Fig. 1;

arcing contacts upon opening of the disconnect- Fig. 3 is a partial cross section taken along ing contacts, and for insuring the complete opplane III- III in Fig. 1 to illustrate the discon- Y eration of the disconnecting contacts after ininecting contacts of the circuit breaker; 40

tiation of such operation. The disconnecting Fig. 4 is a partial cross sectional elevation contacts may also becaused to close in air under through a modied embodiment of the deionizpressure higher than atmospheric pressure to reing chamber illustrated in Fig. 1;

duce arcing which may occur while the contacts Fig. 5 is a cross section taken along plane are approaching engagement. The arcing and V--V in Fig. 4; 45 disconnecting contacts may also be normally Fig. 6 is a cross sectional view similar to that bridged by current carrying contacts if the cirshown in Fig. 5 through another modified emcuit breaker is to carry relatively large currents. bodiment of the deionizing chamber illustrated in The actuating mechanism for the disconnecting Fig. 1;

contacts preferably includes a latched yieldable Fig. '7 diagrammatically illustrates in detail 50 linkage permitting the breaker to open immedithe disconnecting contact actuating means and ately after it is caused to close on an overload or the preferred system of control applicable to the short circuit.l embodiment illustrated in Fig. l;

It is therefore one of the objects of the present Fig. 8 is a cross sectional view similar to Fig. 3 invention to provide a circuit breaker of the but differing therefrom in that one of the conu tacts is provided with a reinforced portion for interlocking the arcing and disconnecting contacts; y

Fig. 9 is an elevational view, partially in cross section, of disconnecting contacts dliering from the contacts illustrated in Fig. 1 in the addition of a latch for interlocking the arcing and disconnecting contact;

Fig. 10 is a side elevational view, partially in cross section, illustrating disconnecting contacts of the sliding tubular type which are caused to approach mutual engagement in air ata pressure higher than atmospheric pressure;

Fig. ll diagrammatically illustrates a portion of the modied control system diiering from the system illustrated in Fig. '7 in that uid is supplied to the arcing chamber of the breaker for a predetermined length of time during each operation'of the breaker;

Fig. l2 is a partial side elevational view, partially in cross section, of a circuit breaker provided with bridging'contacts across the arcing and disconnecting contacts;

Fig. 13 is a partial side elevational view, partially in cross section, of a circuit breaker differing from the embodiment illustrated in Fig. 12 in having one o-f the disconnecting contacts thereof pivoted on the movable bridging contact; and

Fig. 14 diagrammatically illustrates a portion of another modified control system applicable to the control of the modification illustrated in Figs. 12 and 1'3.

It will be understood that elements illustrated in some of the figures may also be utilized in combination with elements illustrated in others of the gures to form further embodiments of the invention.

Referring more particularly to the drawings by characters of reference, Fig. 1 illustrates a circuit breaker including as a constructive element thereof areservoir I6 constituting a source of supply of iluid under pressure, which will be assumed herein to be compressed air, supplied from a suitable compressor (not shown) through a pipe I1 for maintaining the pressure Within the reservoir at a substantially constant value. Reservoir I6 is supported on any suitable base, such as a frame Work |8'of structural steel adapted to be bolted" on a wall. Although in general circuit breakers of the type herein considered are provided with a plurality of similar switch elements to be inserted in the several conductors of an electric circuit, only one such element is shown in Fig. 1 and the circuit breaker Will be described in detail as if it were of the single pole type. circuit breaker comprises an arcing chamber I9 supported on reservoir I6 through a hollow insulator 2|, which also serves to admit air under pressure from reservoir I6 into the chamber. In general it is preferred to form chamber I9 of metal but it will be understood that such chamber may also have walls at least partially of insulating material and may then also constitute a prolongation of insulator 2|. The metallic walls of chamber I9 constitute one of the terminals of the circuit breaker, and a line conductor may be bolted directly thereon or may be connected therewith through an electroresponsive relay 22 operable to cause opening of the circuit breaker upon ilow of excessive current therethrough.

As shown in Fig. 2, a detachable portion or cover 23 of chamber I9 is provided with an orice about which is arranged an annular contact 24 constituting the xed arcing contact of the circuit breaker. The cooperating movable arcing con- Ther tact 26 is mounted on a piston 21 arranged for reciprocatory movement within a cylinder 28 arranged coaxially with contact 24. Cylinder 28 is fastened to an insulating liner 29 of chamber I9 serving to insulate contact 26, piston 21 and cylinder 28 from contact 24 when the arcing contacts are open. Cylinder 28 is partially closed at the upper end thereof by avdiaphragm 3| provided. with apertures for regulating the admission of air from chamber I9 within cylinder 28. Piston 21 is thus rendered operable by means of fluid under pressure introduced within chamber I9 adjacent contacts 24 and 26 for separating such contacts. The contacts cooperate in normally closing the orice of chamber I9, contact 26 being urged into engagement with contact 24 by resilient means such as a spring 32 acting between contact 26 and chamber I9 through diaphragm 3|. Although the circuit breaker is shown as having only one 'pair of arcing contacts, it will be understood that a plurality of serially connected pairs of arcing contacts could also be provided in separate arcing chambers, the movable contact of each pair being urged by a spring acting against such contact and the associated chamber. Al spring acting between two oppositely directed movable contacts severally operable by uid pressure would allow the contact offering the least frictional resistance to open, while the contact offering the greater frictional resistance would remain closed.

The orice .of chamber I9 communicates with an extension of cover 23 forming a nozzle 33 leading into a deionizing chamber 34. Such chamber is preferably frusto-conical in shape having a wall constituted of a metal sheet wound to form a spiral convolute surface. The convolutions of wall 34 thus offer a path of comparatively large cross section to the oW of air therethrough and oppose only a comparatively small resistance thereto, while presenting a large surface for cooling and deionizing such air and for separating therefrom metallic particles detached by the arc from the arcing contact. Chamber 34 also effectively reduces the report caused by the circuit interruption. 'I'he air issuing from the outer fold of wall 34 is preferably directed upward away from grounded or current-carrying members of the circuit breaker by a cylindrical shield 36. 'I'he construction of chamber 34 may also be rendered somewhat simpler by making thechamber o f uniform cross section as illustrated in Fig. 4, wall 34 then being made from a rectangular sheet wound spirally about a cylindrical surface. It may also be advantageous to provide several parallel channels for the iiow of air issuing from nozzle 33, and Wall 34 may accordingly be constituted of a plurality of interleaved spirally Wound sheets as shown in Fig. 6.

Piston 21 is provided with an extension carrying one of the contacts 31 of a disconnecting switch, the arcing and disconnecting contacts being serially connected by the rigid conductive connection between contacts 26 and 31 through piston '21. Contact 31 is preferably formed as a pair of laminated brushes cooperating with another disconnecting contact 38, the space surrounding the cooperating surfaces of contacts 31 and `38 being conned by an insulating shield 39. Contact 38 is formed as a twin blade of which the two halves are spread and pivoted on either side of a bracket 40 forming the second terminal of the circuit breaker, and supported on reservoir ISby means of an insulator 4I similar to insulator 2|. Contact 38 is extended beyond the pivot thereof to form the lever pivotally joined to a connecting rod 42 of insulating material actuated by a crank 43 of a shaft 44 supported for rotary movement on reservoir I6. Shaft 44 is preferably actuated by fluid pressure, such shaft receiving movement from a piston 45 shown in Fig. '7 and arranged for reciprocatory movement within a cylinder 46 through a connecting rod 41 and a double crank 48 to thereby disengage contact 38 from contact 31. Another piston 49 within a cylinder 50 acts on shaft 44 through a connecting rod 5I and crank 48 for engaging contact 38 with Contact 31.` The movement of shaft 44 and of pistons 45 and 49 may be retarded when the pistons approach the ends of their stroke by means of a pair of dashpots 52.

Fig. '7 also diagrammatically illustrates all three switching elements of a three pole circuit r breaker. The connection between connecting rod 5I and crank 48 is effected through a link 53 pivotally connected therebetween to thus form a yieldable linkage. A spring 54 tends to maintain rod 5I and link 53 in alinement, the action of such spring being limited by abutment of the lower end of rod 5I against a projection of a latch The latch is mounted on crank 48 and normally engages the lower end of connecting rod 5I to prevent lateral yielding of the joint of rod 5I and link 53 under the action of piston 49. When the circuit breaker is in the closed position as shown in Fig. 7, contacts 31 and 38 being engaged, latch 56 is disengaged by abutment thereof against a stop 51 which may be arranged on an extension of connecting rod 41.

Cylinder 5U is generally in communication with the atmosphere through a valve 58, and may be supplied with air under pressure from reservoir I6 through the valve upon. actuation thereof by a lever 59. -Lever 59 constitutes the armature of an electromagnet 6I and is actuated upon connection of the magnet coil with a suitable source of current such as a battery 62. Such connection may be effected through contacts 63 of a manually operable control switch 64. The circuit breaker may be opened by connecting the coil of a second electromagnet 66 with battery 62 through contacts 61 of switch 64 and through a segment of an auxiliary drum switch 68 actuated by shaft 44. Electromagnet B6 is provided with a lever armature 69 for actuating a second valve 1I similar to valve 58. Valve 1I controls the admission of air under pressure from reservoir I6 into a cylinder 12 containing a piston 13 acting against the action of a spring 14. Piston 13 actuates a pilot valve 15 controlling the admission of air under pressure from reservoir I6 into a second cylinder 16 containing a piston 11 acting against a spring 18 and actuating a main valve 19. Valve 19 controls the admission of air from reservoir I6 into arcing chamber I9 and into cylinder 46 for causing se'- quential operation of pistons 21 and 45. The connections between valve 19 and cylinder 46 may include means such as a needle valve 8I for controlling the speed of the flow of air to cylinder 46 to delay the action of piston 45.

The piston rods associated with pistons 45 and 49 extend above cylinders 46 and 50 and are shaped with cam surfaces engaging with a pair of followers 82, 83 and maintain the followers in the position shown when the pistons are at either end of the stroke thereof. The cam surfaces also allow the followers to engage the associated levers 59, 69 during substantially the entire stroke of the piston to thereby maintain valves 68 and 1I in the respective positions thereof. Such arrangement insures the completion of the stroke of the pistons after initiation thereof even if switch 64 is moved during such operation. Switch 64 may be provided with contacts 84 cooperating with switch 68 to control a visual signal lamp 86, and may also be provided with contacts 81 cooperating with switch 68 in controlling an auditory signal such as a horn 88.

Assuming the circuit breaker to bein the closed position shown in Figs. 2 and 7, if it is desired to cause the circuit breaker to open, switch 64 is momentarily brought to the position indicated to trip. A circuit is thus completed from battery 62 through contacts 61, switch 68 and coil 66 back to the battery. Electromagnet 66 accordingly attracts the armature 69 thereof, thus causing operation of valve 1I. Valve 1I admits air under pressure from reservoir I6 into cylinder 12, and piston 13 is thereby moved downward to open pilot valve 15. which has a greater diameter than valve 19, and piston 11 is accordingly moved downward and opens Valve 19. l Air under pressure is thus simultaneously admitted into arcing chamber I9 for causing operation of piston 21 and for blowing out the arc drawn between the arcing contacts through the orice of chamber I9, and into cylinder 46. Although the contact disengaging cperation of piston 21 and of piston 45 is thus initiated simultaneously, operation of piston 45 for opening contact 38 must be prevented until after complete opening of contact 26 by piston 21 and extinction of the arc drawn at the arcing contacts has taken' place. Such result may be obtained solely by suitable choice of the relative weights of :if

the members to be actuated, or the operation of piston 45 may be delayed and the speed thereof adjusted by the provision of valve 8l for regulating the rate of admission of air from reservoir I6 into cylinder 46, whereby piston 45 is caused to move slowly relatively to the speed of operation of piston 21.

When air is admitted into chamber I9, the orice of such chamber is closed by the associated arcing contacts and the pressure rapidly increases within the chamber about the. arcing contact and within the space adjacent piston 21. The mass of 'piston 21 and of contacts 26 and 31 carried therecompressed air flowing in chamber I9, radially toward the orifice thereof, i. e. transversely with respect to the arc path. The maximum separation of contacts 24 and 26 is so chosen as to cause the Velocity of the air blast to reach a maximum Value within the space adjacent the contacts, and the dimensions of the orince and of nozzle 33 are Valve 15 admits air into cylinder 16,

so chosen as to cause the arc to be extinguished v tact sa.

particles carried thereby by contact thereof with wall 34.

During such operation, contact 31 is moved.

.through the breaker is thus interrupted, but such circuit must be opened by disconnecting contact 38 because the air blast may not be maintained indefinitely between contacts 24 and 26 and, even if such contacts were maintained separated, the distance therebetween would generally be too small to prevent flashover therebetween upon interruption of the air blast.

At substantially the time of interruption ofv the arc between the arcing contacts, the air pressurewithin cylinder 46 has reached a sufiicient value for causing piston 45 to be actuated to cause disengagement of contacts 31 and 38. Upon initiation of the movement of piston 45, crank 48 driven thereby may move link 53 and connecting rod as -a single member, although such members then form a yieldable joint, because cylinder 5l) is then in communication with the atmosphere and thus does not oppose the movement of piston 49 therein. A slight movement of the crank 48 dsengages stop 51 from latch 56, which then engages connecting rod 5| and thus restores a rigid linkage between crank 48 and piston 49. Follow` ers 82 and 83 operate in response to movement of pistons 45 and 49 to maintain armatures 59 and 69 and valves 58 and 1| in the respective positions thereof to thereby insure completion of the stroke of the pistons.

When the disconnecting contacts have become fully opened, the gap therebetween is sufcient to maintain open the circuit controlled by the circuit breaker, and the arcing contacts may then be reclosed by interruption of the supply of air under pressure to cylinder 28. For this purpose,

while piston 45 is completing its stroke, switch 68 opens the circuit of magnet coil 66. At substantially the end of the stroke of piston 45, follower 83 returns to the position shown and releases armature 69, which is then no longer attracted by coil 66. Valve 1| then returns to the position shown to place cylinder 46 in communication with the atmosphere, whereby piston 45 remains in the position it has reached corresponding to full opening of disconnecting con- Cylinder 12 is also brought into communication with the atmosphere, and pilot valve closes, permitting the air in cylinder 16 to leak out through apertures provided for such purpose. Valve 19 returns to the closed position and ceases to admit air under pressure to chamber I9, and the air within such chamber escapes through the oric thereof, whereupon spring 32 causes reengagement of the arcing contacts. Switch 68 also completes the circuit of lamp 86 thus indicating that the operation of the circuit breaker is then complete. Switch 64 may then be moved into the position marked open", whereby the circuit of lamp 86 is again opened. Switch 64 may however not be moved into the position marked closed as such movement would cause lamp 86 again to be lit.

Tripping of the circuit breaker may be obtained automatically in response to the flow of excessive current through the breaker by means of an overload relay 89 operable to close a pair of contacts bridging contacts 61. Such automatic tripping may also be obtained by means of relay 22, (not shown in Fig. 7) which actuates valve 1| mechanically in response to the ow of excessive current to the circuit breaker. Upon any automatic opening of the circuit breaker while switch 64 remains undisturbed, switch 68 completes the circuit of lamp 86, which indicates that the vcircuit breaker has operated. Switch 68 also completes the circuit of alarm signal 88. By moving switch 64 into the position marked open, contacts 84 are opened, whereby lamp 86 becomes dark, and the latched connection between the spindle of switch 64 and the segment joining contacts 81 becomes unlatched, whereby contacts 81 are opened and alarm sign-a1 88 ceases to function.

If the circuit breaker is open, closure thereof may be initiated by moving switch 64 into the position marked to close. Such movement causes closure of contacts 63, which connect magnet coil 6| with b-attery 62. Valve 58 is thus actuated and admits air under pressure from reservoir I6 into cylinder 50. Connecting rod 5| and link 53, which are then rigidly latched, transmit the movement of piston 49 to crank 48, completion of such movement being insured by the action of followers 82 and 83 which operate in response to movement of pistons 45 and 49 to maintain valves 58 .and 1| in their respective positions during substantially the entire stroke of the pistons. Contact 38 is closed by shaft 44 and, the associated arcing cont-act being already closed, the circuit is completed at the engaging surfaces of contacts 31 and 38. A lashover may then occur between such contacts whilethey are approaching mutual engagement, but such iashover is usually without detrimental eiect as the resulting arc generally carries only current within the normal current carrying capacity of the circuit breaker and is rapidly terminated by engagement of the disconnecting contacts. An extension of the arc from the disconnecting conta'cts to other elements of the circuit breaker is prevented by shie1d39 which confines the space where such arc is produced.

Upon completion of the closure of the' circuit breaker, switch 68 completes the circuit of lamp 86 which indicates that the circuit breaker has operated. Switch 64 may then be moved back into the position marked closed, thereby opening the circuit of lamp 86 and also establishing the latched connection by which the segment associated with contacts 81 may be moved into the position shown, whereby alarm signal 88 may be operated upon, subsequent automatic tripping of the circuit breaker. Such latched connection is broken when switch 64 is moved into the position marked to trip in order to avoid unnecessary operation of alarm signal 88.

If the circuit breaker is closed as above described and the flowof current therethrough immediately reaches an excessive value, as occurs when the breaker is closed on a short circuit, relay 89 or relay 22 immediately cause operation of valve 1| while valve 58 is still admitting air into cylinder 50. vPiston 49 is accordingly maintained in the position shown by the air pressure within cylinder 50, and pistons 21 and 45 are actuated in the manner above described to disengage the arcing and disconnecting contacts. This operation is possible for the reason that, at the moment of full closure of contact 38, connecting rod is disengaged from latch 56. The air pressure acting on piston 45 is transmitted by connecting rod 41 and crank 48 to link 53, the joint between link 53 and connecting rod 5| yielding to move connecting rod 5| sideward against the action of spring 54. A latching of connecting rod 5| by latch 56 is then no longer possible, and piston 45 may complete its stroke to cause opening of the circuit breaker, which thereafter remains in the open position. Upon return of switch 64 to the position marked closed, alarm signal88 operates, thereby indicating automatic tripping ofl the circuit breaker. Such movement of switch 64v also causes deenergization of magnet coil 6| which releases valve 58, whereupon cylinder 50 is put in communication with the atmosphere and piston 49 is moved upward under the Aaction of spring 54 to the uppermost position thereof, at which position connecting rod 5| reengages latch 56. Switch 64 is then moved into the position marked open to interrupt the circuits of lamp 86 and of alarm signal 88.

If it is not desired to rely on the operating characteristics of the contact actuating means for causing sequential operation of the arcing and disconnecting contacts, an interlock may be provided therebetween. AS shown in Fig. 8, the portion of contact 38 normally engaging with contact 31 when the circuit breaker is closed may be made of materially greater thickness than the immediately adjacent portion. The operating means for contact 38 are then so dimensioned that when the arcing contacts are closed, and contact 31 is accordingly in the position shown, it is impossible for piston 45 to move contact 38 out of engagement from contact 31 against the frictional resistance present therebetween. Piston 21, on the contrary, is so dimensioned that upon admission of air from reservoir I6 into chamber I9 such piston may open the arcing contact and move contact 31 downward out of engagement with the reinforced portion of contact 38. Upon completion of such movement, contact 38 no longer oiers any resistance to the action of piston 45 which may move such contact into the open position. Piston 49 is so dimensioned as to be able to reclose contact 38, of which the reinforced portion is beveled, into engagement with contact 31. Such closure is facilitated by the momentum acquired by contact 38 during the closing movement thereof, so that it may' be possible to utilize a piston 49 of the same cross section as piston 45.

Fig. 9 illustrates another interlock consisting of a latch 90 pivoted on piston 21 between the two halves of contact 31. When the circuit breaker is in the closed position as shown, the latch engages with a projection of contact 38 and prevents opening of the latter. When piston 21 moves downward to open the arcing contact, latch 90 slides over the projection of contact 38, which may then be opened by piston 45.

Instead of utilizing disconnecting vcontacts of the pivoted blade and jaw type above considered, contacts of the sliding tubular type may be employed. As shown in Fig. 10, piston 21 may carry a split resilient tubular contact 9| arranged to engage a sliding tubular contact 92. Contact 92 is arranged for 'longitudinal movement within bracket 40 and may be actuated from shaft 44 through gears 93 and through e pinion 94 engaging with a rack 96 integral with contact 92 or fastened thereon. The mechanism includes a member of insulating material 91. Insulating to reclose.

liner 29 is preferably extended downward to a material extent to thereby guide the tip of contact 92 in substantially iiuid tight relation therewith over la substantial distance. Contact 92 is provided with a diaphragm 98 so that liner 29 forms a substantially fluid tight chamber for the cooperating surfaces of contacts 9| and 92 when such contacts are within a predetermined distance of each other. The air Within such chamber is thus brought to an increased pressure during engaging operation of the disconnecting contacts, whereby the dielectric strength of such air is materially increased and arcing between the contacts is thereby prevented until the contacts are closely adjacent each other.

Instead of controlling the closure of valves 15 and 19 by means of auxiliary switch 68, time delay means may be provided for reclosing such valves after a predetermined length of time. As shown in Fig. 11 such means may consist of a piston 13, which "is then provided with a port, and of spring 14, cylinder 12 having no communication with the atmosphere. Cylinder 12 receives air from the reservoir I6 through valve 1| as in the embodiment illustrated in Fig. 7, whereby piston 13 is actuated downward to cause opening of valve 15. Valve 15 admits air into chamber |9 and also admits air into cylinder 46 through a check valve 99. Air also passes from one side of piston 13 to the other side thereof through the port of the piston and, after a predetermined time delay, the pressure on the lower side of the piston reaches a sulcient value to enable spring 14 to reclose valve 15, whereby valve 19 is caused A direct communication is also provided between valve 1| and cylinder 46 to provide a continuous supply of air to cylinder 46 during the stroke of piston 45. To avoid premature operation of piston 45 upon operation of valve 1|, such additional connection is completed through a port in the wall of cylinder 45 which is uncovered by piston 45 4after such piston has made part of its stroke under the action Cil of the air supplied through valve 19. Check valve 99 prevents the supply of air from cylinder 46 to arcing chamber I9 after closure of valve 19.

In circuit breakers designed for carrying and interrupting comparatively large currents, it is lnot always desirable to provide disconnecting contacts and arcing contacts capable of continuously carrying the rated current of the circuit breaker. It is then preferable to provide cooperating xed and movable contacts for bridging the arcing and disconnecting contacts. As shown in Figs. 12 and 13, the arcing and disconnecting contacts may be bridged by a xed contact |0| mounted 'on chamber |9 cooperating with a movable contact |02 pivoted on bracket 40 and actuated by connecting rod 42. Contact 38 may also be pivoted on bracket 40 as shown in Fig. 12, or may be pivoted on contact |02 as shown in Fig. 13. Contact 38 is then actuated by pistons 45 and 49 through contact |02. Contacts 38 and |02 are provided with cooperating surfaces and are maintained in abutment at such surfaces by means of a spring |03. It will be observed that contact |02 may be actuated by piston 45 or piston 49 only while the associated arcing and disconnecting contacts are in engaged position. The operating mechanism of the circuit lbreaker may then be arranged as shown in Fig. 14. In such figure, valve 1| admits air directly into cylinder 46 to cause movement of piston 45. When the piston has moved a certain distance, contact |02 is opened thereby while contact 38 remains in engagement with contact 31 against the action of spring |03 as a result of the friction between such contacts, or of the presence of an interlock therebetween. Piston then uncovers a port in cylinder 46 for admitting air from cylinder 46 into cylinder 12, whereby the arcing and disconnecting contacts of the circuit breaker are caused to open sequentially, the arcing contacts reclosingimmediately upon completion of the stroke of piston 45 under the control of switch 68. The circuit breaker is reclosed by movement of piston 49, which actuates contact |02. Such contact urges contact 38 by means'of the cooperating surfaces of contacts |02 and 38 in such a manner that contact 38 recloses before contact |02. Fig. 14 also illustratesa modified form of some of the details of the operating mechanism of the circuit breaker. Spring 54 is shown acting between connecting rods 41 and 5|, and stop 51 is shown carried by a fixed member instead of being carried by connecting rod 41. The followers for locking valves 58 and 1| during the vstroke of pistons 45 and 49 are shown as rigidly coupled and responsive to movement 'of piston 45 into the one or the other end position thereof.

Although but a few embodiments of the present invention have been illustrated and described, it will be apparent to those skilled in the art that various changes and modiiicationsmay be made therein without departing from the spirit of the invention or from the scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

1'. An electric circuit breaker including a plurality of relatively movable arcing contacts, means operable by fluid pressure for actuating one of said arcing contacts, a disconnecting contact in mechanical and conductive connection with said one of said relatively movable contacts, a second disconnecting contact cooperating with the first said disconnecting contact, means operable by fluid pressure independently of said movable arcing contact actuating means for actuating the second said disconnecting contact, means for simultaneously initiating the operation of the first and the second said contact actuating means, and means for preventing operation of the second said contact actuating means until after operation of the first said contact actuating means.

2. An electric circuit breaker including a plurality of relatively movable arcing contacts, means operable by fluid pressure for disengaging said arcing contacts, a disconnecting contact in mechanical and conductive connection with one of said relatively movable contacts, a second disconnecting contact cooperating With the first said disconnecting contact, means operable by iluid pressureindependently of said movable arcing contact actuating means for engaging and disengaging the second. said disconnecting. contact with and from the rst said disconnecting contact, means for initiating contact disengaging operation of the rst and the second said means, and means for preventing the said operation of `the second said means until after operation of the first said means.

3. An electric circuit breaker including a plurality of relatively movable arcing contacts, means operable by fluid pressure for disengaging said contacts, a disconnecting contact in mechanical and conductive connection with one of said relatively movable contacts, a second disconnecting contact cooperating with the rst said disconnecting contact, means operable by iiuid pressure for engaging and disengaging the second said disconnecting contact4 with and from the ilrst said disconnecting contact, means for supplying fluidunder pressure'- to the first and the second said means to cause sequential contact disengaging operation thereof, means responsive to disengaging operation of the second said means for interrupting the supply of fluid under pressure to the first said means, and resilient means for causing reengagement of said arcing contacts upon interruption of the supply of fluid under pressure to the iirst said means.

4. An electric circuit breaker including a pair of cooperating arcing contacts, a pair of cooperating disconnecting contacts serially connected with said arcing contacts, cooperating xed and movable contacts for bridging the first and the second said pairs of contacts, and means operable by uid pressure for actuating said movable bridging contact only when the rst and the second said pairs of contacts are in engaged position. i

5. An electric circuit breaker including a plurality of relatively movable arcing contacts,

means operable by iluld pressure for disengaging said arcing contacts, a disconnecting contact in mechanical and conductive connection with one of said relatively movable contacts, a second disconnecting contact cooperating with the rst said disconnecting contact, means operable by uid pressure for engaging and disengaging the second said disconnecting contact with and from the first said disconnecting contact, means for supplying iiuid under pressure to the rst and the 'second said means to cause sequential contact disengaging operation thereof, means responsive to disengaging operation of the second said means for interrupting the supply of iiuid under pressure to the first said means, resilient means for causing reengagement of said arcing contacts upon interruption of the supply of duid under pressure to the first said means, and means for guiding the second said disconnecting contact and forming a substantially fluid tight chamber for the cooperating surfaces of said disconnecting contacts when said disconnecting contacts are within a predetermined distance of each other, whereby the air within said chamber is brought to an increased pressure during engaging operation of said disconnecting contacts.

6. An electric circuit breaker including a supply of fluid under pressure, an arcing chamber `carrying an insulated cylinder and having an orifice coaxial with said cylinder, a piston arranged for relatively rapid movement Within said cylinder upon admission of fluid under pressure into said chamber, cooperating arcing contacts one of which is mounted about the orifice and the other of which is mounted on said piston, resilient means urging said contacts into mutual engagement to close the orice, a disconnecting contact arranged o`n said piston in conductive connection with the arcing contact mounted thereon, a second disconnecting contact cooperating with the first said disconnecting contact,

means relatively slowly operable by iiuid pressure for disengaging the second said disconnecting contact from the first said disconnecting contact, and means for simultaneously connecting said chamber and said contact disengaging means' with the supply of iiuid pressure.

7. An electric circuit breaker including a supply offluidunder pressure, an arcing chamber carrying an insulated cylinder and having an oriilce coaxial with said cylinder, a piston arranged for movement within said cylinder upon admission of fluid under pressure into said chamber, cooperating arcing contacts one of which is mounted about the oriilce and the other of which is mounted on said piston., resilient means urging said contacts into mutual engagement to close the orifice, a disconnecting contact arranged on said piston in conductive connection with the arcing contact mounted thereon, a second disconnecting contact cooperating with the first said disconnecting contact, means operable by fluid pressure for disengaging the second said disconnecting contact from the iirst said disconnecting contact, means for simultaneously connecting said chamber and said contact disengaging means with the supply of iluid pressure, and means for delaying the action of said contact disengaging means.

8. An electric circuit breaker including a plurality o1' relatively movable arcing contacts, means operable by fluid pressure for actuating one oi' said arcing contacts, a disconnecting contact in mechanical and conductive connection with said one of said relatively movable contacts, a second disconnecting contact cooperating with the iirst said disconnecting contact, means operable by fluid pressure for actuating the second said disconnecting contact, means for simultaneously initiating the operation oi the ilrst and second said contact actuating means, and means for insuring completion oi the movement of the second said contact actuating means.

9. An electric circuit breaker including a supply oi fiuid under pressure, an arcing chamber having cooperating arcing contacts, means operable by iluid pressure within said chamber for separating s'aid arcing contact, a disconnecting contact in mechanical and conductiveconnection with one of said arcing contacts, a second disconnecting contact cooperating with the iirst said disconnecting contact, a cylinder containing a piston operable by iluid pressure for disengaging the second said disconnecting contact from the ilrst said disconnecting contact, a valve for connecting said chamber and said cylinder with said supply, and means responsive to movement of said piston for maintaining said valve open during substantially the entire stroke ot said piston.

10. An electric circuit breaker including a supply of iluid under pressure, an arcing chamber having cooperating arcing contacts. means operable by iiuid pressure within said chamber for separating said arcing contacts. a disconnectins contact in mechanical and conductive connection with one of said arcing contacts, a second disconnecting contact cooperating with the ilrst said disconnecting contact, a cylinder containing a piston operable by fluid pressure for disengaging the second said disconnecting contact from the first said disconnecting contact, a valve for connecting said chamber and said cylinder with said supply of fluid pressure, another cylinder containing a piston operable by iiuid pressure for engaging the second said disconnecting contact with the ilrst said disconnecting contact, a valve for connecting the second said cylinder with said supply, and means responsive to movement of said pistons in response to operation of one of said'valves for maintaining said valves in their respective positions during substantially the entire stroke of said pistons.

11. An electric circuit breaker including a supply oi iluid under pressure, an arcing chamber having cooperating arcing contacts, means operable by iluid pressure within said chamber for separating said arcing contacts, a disconnecting contact in mechanical and conductive connection with one of said arcing contacts, a second disconnectng contact cooperating with the ilrst said disconnecting contact, a cylinder containing a piston operable by uid pressure for disengaging the second said disconnecting contact from the ilrst said disconnecting contact, a valve ior connecting/said chamber and said cylinder with said supply of iluid pressure, another cylinder containing a piston operable by iluid pressure for engaging the second said disconnecting contact with the first said disconnecting contact, a valve for connecting the second said cylinder with said supply, a latched yieldable linkage in the connection between the second said piston and the second said disconnecting contact, and means for unlatching said linkage when said disvco'nnccting contacts are engaged, whereby said connection may yield and the ilrst said pistonmay disengage said disconnecting contacts when said valves are simultaneously open.

12. An electric circuit breaker including a supply of fluid under pressure, an arcing chamber having an orifice, a pair of cooperating contacts operable to close said oriilce, means operable by iluid pressure within said chamber for separating said contacts, valve means for controlling the admission of said iluid from said supply into said chamber to cause operation oi said contact separating means and for blowing out the arc drawn between said contacts through the oriiice. means for causing opening ot said valve means. and time delay means for causing said valvemeans to reclose.

ARNOLDHALLIR.

HANS THOMHEN. 

